The 37-year has scaled the heights of the NBA, winning four titles and two league Most Valuable Player awards, and nothing fazes him, not even the prospect of facing the top-seeded Miami Heat in a decisive seventh game of the championship series.
While many players, including Miami's LeBron James, have confessed to feeling nervous about Thursday's do-or-die encounter, Duncan was nonchalant about the enormity of the contest.
"I prepare for every game exactly the same," he said.
"That's why I feel every game is exactly the same. Obviously the pressure is there, the stage is there, the energy is there but preparation doesn't change."
Duncan has already experienced the pressure-cooker atmosphere of playing in a NBA Finals Game Seven, against the Detroit Pistons in 2005, and he came through with flying colours.
He scored 25 points in his team's 81-74 win and was named the Finals' MVP for the third time in his career.
Duncan has been in vintage form against Miami in this year's Finals. In Tuesday's Game Six, he scored 30 points but to no avail as Miami engineered a late comeback to snatch victory.
Some of his team-mates were devastated by the loss, fearing they may have blown their chances of winning the title with the decider to be held in Miami but not Duncan.
"Some people use it the right way, some people are hurt by it but I don't feel I'm affected by it," he said. "I use it however I can, and love the environment."
With an honours degree in psychology, Duncan knows the value of sticking to the popular sportsman's mantra of taking it one game at a time.
His level-headed approach can be traced back to his upbringing. Born and raised in the Virgin Islands, his first love was swimming. His older sister competed at the 1988 Seoul Olympics but Duncan ditched his goggles for hoops when a hurricane destroyed the only Olympic-sized pool on his island.
Drafted first overall in 1997, he has played his entire NBA career with the Spurs under head coach Gregg Popovich.
Together they formed one of basketball's oddest but most successful couples, teaming up to win four championships and now the chance of a fifth.
"You know what, it's all about just winning the title," said Duncan. "It's a great story for everybody else, but we're here for one reason. One reason only: It's to try to win this game tomorrow."